package cn.lbwfree.day3_26;

import java.util.Scanner;
/**
 * @date:2020年3月26日
 * @author:lbwfree
 * number:BASIC-22 FJ的字符串
 */
	//A1 = “A”
	//A2 = “ABA”
	//A3 = “ABACABA”
	//A4 = “ABACABADABACABA”
public class FjString {
	public static void main(String[] arg) {
		Scanner inScanner = new Scanner(System.in);
		int n = inScanner.nextInt();
		if(n<=0||n>26)
		{
			return;
		}
		String[] temp = new String[n+2];
		char t ='A';
		temp[0]="";
		for (int i = 1; i <= n; i++) {
			temp[i] = temp[i-1]+(char)(t+i-1)+temp[i-1];
		}
		System.out.println(temp[n]);
	}
}
